TERT promoter mutation as a prognostic marker in patients with advanced urothelial carcinoma treated with immune checkpoint inhibitors.

Abstract

476 Background: Reliable predictive markers are lacking in patients (pts) with locally advanced or metastatic urothelial carcinoma (aUC) treated with immune checkpoint inhibitors (ICI). We sought to determine whether specific genomic alterations could be used to predict overall survival (OS) in this patient population. Methods: We undertook a retrospective cohort study of pts with aUC who received ICI and underwent genomic profiling by next-generation sequencing (NGS). All patients underwent NGS using commercially available platforms (e.g. Foundation Medicine, Strata, Invitae), or testing on the CLIA-certified institutional panel UCSF500. Associations between the 20 most frequently altered genes and OS were first examined by Cox regression. Genes with a p <0.1 on univariate analysis and relevant clinical variables were then included in a multivariable analysis. Results: We identified 78 pts treated with ICI for aUC with available genomic profiling results. Median age at ICI initiation was 71; the majority of patients had visceral metastases (70.5%), ECOG performance status ≤1 (62.8%) and received ICI in the post-platinum setting (52.6%). Objective response rate in this cohort was 35.9%, median progression free survival was 4.0 months (95% CI 2.6-10.5) and median OS was 17.5 months (95% CI 14.1-NR) from ICI start. The most commonly altered genes were the TERT promoter (TERTp) (61%), TP53 (52%), RB1 (31%), CDKN2A(29%) and CDKN2B (27%). On univariable analysis there was a trend towards longer OS in pts with TERTp mutations (HR 0.53, 95% CI 0.27-1.06, p = 0.07), and shorter OS in pts with CDKN2B mutations (HR 1.91, 95% CI 0.98-3.73, p = 0.06). Both mutations were included in a multivariable analysis. After adjusting for known prognostic variables (ECOG PS, visceral metastases, albumin, hemoglobin, body mass index [BMI], neutrophil to lymphocyte ratio [NLR], and histology), the presence of a TERTp mutation was significantly associated with improved OS (HR 0.30, 95% CI 0.10-0.93, p = 0.04; Table). Conclusions: The presence of a TERTp mutation was an independent predictor of improved OS in a cohort of aUC pts treated with ICI. Other common mutations and clinical variables were not associated with OS on a multivariable analysis. These findings are hypothesis-generating and prospective validation is needed. [Table: see text]